The invention relates generally to power supplies and more specifically to regulated power supplies, particularly switching regulators.
One particular application for regulated power supplies is ion laser power supplies. The important factors are weight, speed, complexity, reliability and conducted emissions. Thus, a simple, inexpensive, compact and light weight design is particularly advantageous for use in an ion laser.
The following have been utilized in ion laser power supplies. A magnetic amplifier is reliable but heavy. A motor generator set is heavy and noisy. A carbon pile is erratic. A motor driven Variac has heavy brush problems. A buck boost transformer is heavy and requires manual tap changes. Phase controlled rectifiers include complex gate drive circuits and produce conducted emissions. Series pass transistors require many power semiconductors and are expensive to build. The standard switching regulator is efficient but includes expensive magnetics and complex snubbing. Thus, none of the available types of power supplies are ideal for an ion laser.
U.S. patent application Ser. No. 754,036 filed July 11, 1985, describes a dissipative switched resistor regulator in which current flow through a resistor electrically connected to a load is controlled by varying the duty cycle of switching the resistor into electrical connection between a power source and the load; the switching resistor may be in series or parallel to the load. However, since there is always a series resistance between the source and the load when the switch is closed (the switching resistor in the series regulator configurations), there is a high minimum voltage drop (when the series switch is closed all the time or the parallel switch is open all the time) across this series resistance, which results in poor efficiency since the full source voltage cannot be applied to the load. The problem cannot be solved merely by decreasing the series resistance since this results in increased peak currents which may exceed the capability of the switch in the regulator, and also in increased capacitor ripple currents.
Accordingly, it is an object of the invention to provide an improved switching regulator.
It is also an object of the invention to provide a regulated power supply for an ion laser.
It is another object of the invention to provide a regulated power supply which is simple, inexpensive, light weight and compact in design.
It is a further object of the invention to improve the switched resistor regulator by decreasing the minimum voltage drop to the load.